feat(文件预览): 添加对PDF、Word和Excel文件的预览支持

添加新的文件预览组件，支持PDF、Word(docx)、Excel(xlsx/xls)文件类型预览
重构图片预览为独立组件，并添加相关依赖包

klp-ui/package.json

@@ -40,6 +40,9 @@
     "@babel/parser": "7.7.4",
     "@jiaminghi/data-view": "^2.10.0",
     "@riophae/vue-treeselect": "0.4.0",
+    "@vue-office/docx": "^1.6.3",
+    "@vue-office/excel": "^1.7.14",
+    "@vue/composition-api": "^1.7.2",
     "axios": "0.24.0",
     "bpmn-js-token-simulation": "0.10.0",
     "clipboard": "2.0.8",
@@ -74,6 +77,7 @@
     "vue": "2.6.12",
     "vue-count-to": "1.0.13",
     "vue-cropper": "0.5.5",
+    "vue-demi": "^0.14.10",
     "vue-flv-player": "^1.0.3",
     "vue-konva": "^2.1.7",
     "vue-meta": "2.4.0",